This invention relates to a method for producing a centrifugally cast concrete product, and more specifically to a method for producing a centrifugally cast concrete product by charging concrete into a form using a pump to cast the concrete centrifugally, which provides minimized generation of sludge during centrifugal casting.
In a conventional centrifugal casting method for the production of hollow concrete products such as concrete pole or concrete pile, the mixed concrete is charged using a pump into a cylindrical form, and the form is rotated at a high speed to cast the concrete by a centrifugal force, thereby squeezing out part of mixed water and obtaining a dense concrete product.
Recently, it has become possible, using a high water reducing agent, to produce a high-strength, centifugally cast concrete product by centrifugally casting a concrete which has a considerably reduced water/cement ratio, and now most factories are centrifugally casting concrete which contains a high water reducing agent.
This method can produce a high-strength product, however, it has been defective in that since the addition of the high water reducing agent results in an increased thixotropy of the concrete, material separation of the concrete is accelerated by the centrifugal force and vibration, generating increased amounts of sludge.
The sludge is a strong alkali, which has required considerable expense and labor for disposal at the factories.